ceph: simplify arguments and return semantics of try_get_cap_refs

The return of this function is rather complex. It can return 0 or 1,
and in the case of a 1 return, the "err" pointer will be filled out.
This necessitates a lot of copying of values.

We can achieve the same effect by just returning 0, 1 or a negative
error code, and drop the "err" argument from this function.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

1 files changed, 30 insertions, 46 deletions

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index 90090a56899e..9e0b464d374f 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -2525,9 +2525,14 @@ static void __take_cap_refs(struct ceph_inode_info *ci, int got,
  * to (when applicable), and check against max_size here as well.
  * Note that caller is responsible for ensuring max_size increases are
  * requested from the MDS.
+ *
+ * Returns 0 if caps were not able to be acquired (yet), a 1 if they were,
+ * or a negative error code.
+ *
+ * FIXME: how does a 0 return differ from -EAGAIN?
  */
 static int try_get_cap_refs(struct ceph_inode_info *ci, int need, int want,
-                            loff_t endoff, bool nonblock, int *got, int *err)
+                            loff_t endoff, bool nonblock, int *got)
 {
         struct inode *inode = &ci->vfs_inode;
         struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
@@ -2547,8 +2552,7 @@ again:
         if ((file_wanted & need) != need) {
                 dout("try_get_cap_refs need %s file_wanted %s, EBADF\n",
                      ceph_cap_string(need), ceph_cap_string(file_wanted));
-                *err = -EBADF;
-                ret = 1;
+                ret = -EBADF;
                 goto out_unlock;
         }
 
@@ -2569,10 +2573,8 @@ again:
                 if (endoff >= 0 && endoff > (loff_t)ci->i_max_size) {
                         dout("get_cap_refs %p endoff %llu > maxsize %llu\n",
                              inode, endoff, ci->i_max_size);
-                        if (endoff > ci->i_requested_max_size) {
-                                *err = -EAGAIN;
-                                ret = 1;
-                        }
+                        if (endoff > ci->i_requested_max_size)
+                                ret = -EAGAIN;
                         goto out_unlock;
                 }
                 /*
@@ -2607,8 +2609,7 @@ again:
                                          * task isn't in TASK_RUNNING state
                                          */
                                         if (nonblock) {
-                                                *err = -EAGAIN;
-                                                ret = 1;
+                                                ret = -EAGAIN;
                                                 goto out_unlock;
                                         }
 
@@ -2637,8 +2638,7 @@ again:
                 if (session_readonly) {
                         dout("get_cap_refs %p needed %s but mds%d readonly\n",
                              inode, ceph_cap_string(need), ci->i_auth_cap->mds);
-                        *err = -EROFS;
-                        ret = 1;
+                        ret = -EROFS;
                         goto out_unlock;
                 }
 
@@ -2647,16 +2647,14 @@ again:
                         if (READ_ONCE(mdsc->fsc->mount_state) ==
                             CEPH_MOUNT_SHUTDOWN) {
                                 dout("get_cap_refs %p forced umount\n", inode);
-                                *err = -EIO;
-                                ret = 1;
+                                ret = -EIO;
                                 goto out_unlock;
                         }
                         mds_wanted = __ceph_caps_mds_wanted(ci, false);
                         if (need & ~(mds_wanted & need)) {
                                 dout("get_cap_refs %p caps were dropped"
                                      " (session killed?)\n", inode);
-                                *err = -ESTALE;
-                                ret = 1;
+                                ret = -ESTALE;
                                 goto out_unlock;
                         }
                         if (!(file_wanted & ~mds_wanted))
@@ -2707,7 +2705,7 @@ static void check_max_size(struct inode *inode, loff_t endoff)
 int ceph_try_get_caps(struct ceph_inode_info *ci, int need, int want,
                       bool nonblock, int *got)
 {
-        int ret, err = 0;
+        int ret;
 
         BUG_ON(need & ~CEPH_CAP_FILE_RD);
         BUG_ON(want & ~(CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO|CEPH_CAP_FILE_SHARED));
@@ -2715,15 +2713,8 @@ int ceph_try_get_caps(struct ceph_inode_info *ci, int need, int want,
         if (ret < 0)
                 return ret;
 
-        ret = try_get_cap_refs(ci, need, want, 0, nonblock, got, &err);
-        if (ret) {
-                if (err == -EAGAIN) {
-                        ret = 0;
-                } else if (err < 0) {
-                        ret = err;
-                }
-        }
-        return ret;
+        ret = try_get_cap_refs(ci, need, want, 0, nonblock, got);
+        return ret == -EAGAIN ? 0 : ret;
 }
 
 /*
@@ -2734,7 +2725,7 @@ int ceph_try_get_caps(struct ceph_inode_info *ci, int need, int want,
 int ceph_get_caps(struct ceph_inode_info *ci, int need, int want,
                   loff_t endoff, int *got, struct page **pinned_page)
 {
-        int _got, ret, err = 0;
+        int _got, ret;
 
         ret = ceph_pool_perm_check(ci, need);
         if (ret < 0)
@@ -2744,21 +2735,19 @@ int ceph_get_caps(struct ceph_inode_info *ci, int need, int want,
                 if (endoff > 0)
                         check_max_size(&ci->vfs_inode, endoff);
 
-                err = 0;
                 _got = 0;
                 ret = try_get_cap_refs(ci, need, want, endoff,
-                                       false, &_got, &err);
-                if (ret) {
-                        if (err == -EAGAIN)
-                                continue;
-                        if (err < 0)
-                                ret = err;
-                } else {
+                                       false, &_got);
+                if (ret == -EAGAIN) {
+                        continue;
+                } else if (!ret) {
+                        int err;
+
                         DEFINE_WAIT_FUNC(wait, woken_wake_function);
                         add_wait_queue(&ci->i_cap_wq, &wait);
 
-                        while (!try_get_cap_refs(ci, need, want, endoff,
-                                                 true, &_got, &err)) {
+                        while (!(err = try_get_cap_refs(ci, need, want, endoff,
+                                                        true, &_got))) {
                                 if (signal_pending(current)) {
                                         ret = -ERESTARTSYS;
                                         break;
@@ -2767,19 +2756,14 @@ int ceph_get_caps(struct ceph_inode_info *ci, int need, int want,
                         }
 
                         remove_wait_queue(&ci->i_cap_wq, &wait);
-
                         if (err == -EAGAIN)
                                 continue;
-                        if (err < 0)
-                                ret = err;
                 }
-                if (ret < 0) {
-                        if (err == -ESTALE) {
-                                /* session was killed, try renew caps */
-                                ret = ceph_renew_caps(&ci->vfs_inode);
-                                if (ret == 0)
-                                        continue;
-                        }
+                if (ret == -ESTALE) {
+                        /* session was killed, try renew caps */
+                        ret = ceph_renew_caps(&ci->vfs_inode);
+                        if (ret == 0)
+                                continue;
                         return ret;
                 }